Single endless strand mounted in a series of parallel convolutions as a fibrous web supporting surface in a papermaking machine

ABSTRACT

A porous supporting structure for a fluid impregnated web or sheet in a papermaking machine is composed of a a single endless strand mounted to travel in an endless path over a roll assembly with adjacent, machine direction convolutions of strand being in parallel relation to form a moving supporting surface for the web. Multiple single strand systems located in the longitudinal direction of the paper-making system can be employed, the individual endless strand systems constituting web support for the forming, pressing, and drying sections. Adjacent strand systems have a common support roll and convolutions of the strands associated with adjacent roll assemblies pass over the common roll to integrate the strands and provide a continuous supporting surface for the paper web. Each web supporting surface can be provided with areas of different physical characteristics, such as porosity, by adding or removing convolutions from certain areas of the web supporting surface or by substituting strands of different physical characteristics.

limited States Patent Orbison et al.

Nov. 6, 1973 Inventors: Frank H. Orbison; Howard M.

Helland, both of Appleton, Wis.

Assignee: Appleton Mills, Appleton, Wis.

Filed: Sept. 17, 1970 Appl. No.: 72,998

US. Cl 162/348, 34/162, 34/236,

100/118, l62/DIG. 1, 198/129, 198/190, 226/170 Int. Cl. D21f l/l0, D21f 7/12, B65g 15/12 [58] Field of Search 162/348, 289, 358, 162/354, 290, DIG. 1; 226/170, 171, 172; 27l/45,69;34/111,l16,123,153, 152,155, 156, 236, 162; 210/213; 100/118; 198/190, 129

[56] References Cited UNITED STATES PATENTS 3,531,371 9/1970 Jordansson et al. 162/290 X 1,701,226 2/1929 Collins 2,987,988 6/1961 Robledano... 3,417,488 12/1968 McCoy 2,296,897 9/1942 Billing et al.. 3,570,653 3/1971 Cullen 3,003,249 10/1961 Templeton 198/190 X FOREIGN PATENTS OR APPLICATIONS 634,224 3/1950 Great Britain 198/190 I811 I81: 5 Z/ L Primary ExaminerS. Leon Bashore Assistant Examiner-Richard H. Tushin Att0rneyAndrus, Sceales, Starke and Sawall [57] ABSTRACT A porous supporting structure for a fluid impregnated web or sheet in a papermaking machine is composed of a a single endless strand mounted to travel in an endless path over a roll assembly with adjacent, machine direction convolutions of strand being in parallel relation to form a moving supporting surface for the web. Multiple single strand systems located in the longitudinal direction of the paper-making system can be employed, the individual endless strand systems constituting web support for the forming, pressing, and drying sections. Adjacent strand systems have a common support roll and convolutions of the strands associated with adjacent roll assemblies pass over the common roll to integrate the strands and provide a continuous supporting surface for the paper web. Each web supporting surface can be provided with areas of different physical characteristics, such as porosity, by adding or removing convolutions from certain areas of the web supporting surface or by substituting strands of different physical characteristics.

14 Claims, 8 Drawing Figures VPATENTEDHBY 5-1975 Y 3.770.581

1 SHEET 10F 4 FIGJ INVENTOR FRANK H ORBIS N F i QWARD M HELLAND Attorneys PATENTEnuuv 61m 3.770.581

sum 2 or 4 1NVENTOR5 FRANK H. ORBISON HOWARD M HELLAND VII/4! Attorneys PATENTEDRBY s m SHEET 3 UF 4 INVENTORS FRANKH QRBISON I-JOWARD' M HELLAND I Mid/ Attorneys PATENTEBnnv s 1915 3,770,581 SHEET 1 or .4

, FIG 8 INVENTORS' FRANK H. ORBISON P I OWARD M. HELLAND Attorneys SINGLE ENDLESS STRAND MOUNTED IN A SERIES OF PARALLEL CONVOLUTIONS AS A FIBROUS WEB SUPPORTING SURFACE IN A PAPERMAKING MACHINE This invention relates to a porous supporting structure for a web or sheet containing a fluid impregnant, and more particularly to a papermaking machine having a series of paper web supporting structures which are integrated to provide a continuous supporting surface for the paper web throughout the machine.

In a papermaking machine diluent water used to prepare cellulose fibers for sheet formation must be removed. The water carried by the formed sheet must beextracted by drainage and pressing, and most of the water remaining in the pressed sheet must be driven out by heat in order to create a paper product. While these water removing operations are taking place, the paper web or sheet must be supported and conveyed by a I structure which satisfies both water removal and paper finish requirements. Since gravity, vacuum, pressure, absorption and vaporization are successively used to control the appropriate rate of maximum water removal and also to satisfy the finish or smoothness requirements of the sheet, the structures which support and convey the paper web control the success of the papermaking operation.

The papermaking machine has three sections: forming, pressing and drying. Each section has distinctive supporting and conveying structures which provide different water removing rates and different paper surface smoothness influences in order to simultaneously provide for the imposed process and product requirements described above. The structures used to support and convey the paper web in each of these sections are generally described, respectively, as forming fabrics, web felts, and dryer fabrics.

In the conventional papermaking machine the wet paper web must be transferred successively from the forming fabric to the wet felt to the dryer fabric. At the transfer areas the paper web isinormally unsupported and speed differential between the sections of the papermaking machine, or flutter of the unsupported web, may cause breakage of the web at the transfer area. Breaking of the web at the transfer area is a serious problem because the unsupported web will not rethread itself over the rolls and it is necessary to manually rethread the severed end of the web through the various roll assemblies of the machine.

The paper web may be supported at the transfer area by use of what is commonly referred to as a suction transfer. The The suction transfer requires a separate fabric and a roll assembly including a suction roll. The paper web is held against the fabric on the suction roll as it is transferred from one section of the papermaking machine to the next. However, the suction transfer not only requires additional expensive equipment, but the paper web is held up against the suction roll which is acting against gravity and a decrease or loss of suction will result in a dropping of the paper web.

It has been recognized that traditional web supporting structures of the papermaking machine, consisting of both machine direction elements or warp yarns and cross direction elements, limit their effectiveness in the primary function of water removal. The copending patent application Ser. No. 10,412, filed Feb. 11, 1970, now abandoned, is directed to a supporting structure for a paper web or sheet in which the cross direction elements are eliminated and a single endless strand is arranged in a series of machine direction loops or convolutions and serves to support the paper web in travel through each of thepaper-making sections. The pres-' ent invention is an improvement to that patent application and serves to integrate the single strand web supporting structure of each of the sections of the papermaking machine to provide a continuous supporting surface for the paper web throughout the machine. ln one form of the invention, the web supporting surface for each of the sections of the machine is composed of a single endless strand which is arranged to travel in an endless path over a roll assembly which is composed of a series of rolls. The roll assemblies of adjacent sections of the machine have a common roll which is a part of each roll assembly. A group of turns or convolutions of the strand of each adjacent section of the machine passes over the common roll so that the strands of each section are integrated on the common roll, thereby forming an uninterrupted supporting surface for the paper web to enable the web to be transferred from one section to the other while continuously supported.

In a second form of the invention, the same single strand is employed to provide the web supporting surface in more than one section of the papermaking machine. For example, a single strand is utilized to provide the web supporting surface in both the forming section and the drying section, while a second strand having different physical characteristics than the first strand is employed as the web supporting surface in the press section.

Utilizing the same concept with the strand of a single section, the porosity of various portions or areas of the web supporting surface can be varied. This can be accomplished by utilizing a series of rolls to support the turns or convolutions of the strand defining the web supporting surface and a group of convolutions travels the length of the web supporting surface, while other groups of convolutions travel only portions of the length of the supporting surface so that not all of the convolutions extend the length of the web supporting surface. As certain convolutions are dropped out from or added to the web supporting surface a lesser or greater number of convolutions are present in certain areas with the result that the porosity of that portion of the web supporting surface is correspondingly varied.

The physical characteristics of the web supporting surface can also be varied by substituting strands of different composition, construction or diameter in various areas of the web supporting structure. In this manner, merging or comingling of strands of different physical properties can vary the characteristics of the supporting surface as desired.

face for the paper web from the time the web is formed at the slice until it leaves the dryer section. As the paper web is supported at all times during forming, pressing and drying any possibility of the web breaking in unsupported areas is eliminated. By providing continuous support for the paper web throughout the extent of the papermaking machine, the speed of travel of the paper web can be substantially increased and thus results in improved economy in the papermaking operation.

The use of the single strand itself has distinct advantages over fabrics having cross machine elements in that it improves the rate of water extraction from the paper web and this also enables the speed of travel of the paper web to be substantially increased. In addition, the single endless strand can be replaced if damaged or worn by merely severing the strand, attaching a new strand to the severed end, and as the strand travels through the winding pattern, the strand will be drawn through the desired pattern on the roll assembly.

As a further advantage, it is possible to perform desired operations on the strand outside of the web supporting surface, such as sizing treatments, lubrication, cleaning and the like.

The use of the single strand greatly simplifies handling and transporting requirements, for the strand is shipped in spool or coiled form and at the site of the papermaking machine the coiled strand is merely fed through the machine in the desired path of travel.

Other objects and advantages will appear in the course of the following descriptions.

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a diagrammatic perspective view of a Fourdrinier papermaking machine utilizing the web supporting structure of the invention;

FIG. 2 is a side elevation of the machine of FIG. 1;

FIG. 3 is a diagrammatic view showing the path of travel of the various strands in the papermaking operation;

FIG. 4 is a diagrammatic side elevation of a section of a papermaking machine utilizing a single strand and having a web supporting surface of varying porosity;

FIG. 5 is a diagrammatic plan view of the structure shown in FIG. 4;

FIG. 6 is a diagrammatic side elevation of a modified form of the invention;

FIG. 7 is a plan view of the structure of FIG. 6; and

FIG. 8 is a diagrammatic plan view of a further modified form of the invention.

FIG. 1 illustrates diagrammatically a papermaking machine including a F ourdrinier section 1, a press section 2, and a dryer section 3. The Fourdrinier section includes a headbox 4 which supplies a slurry of paper pulp through a slice 5 onto a web supporting surface 6 to form a paper web or sheet 7. The supporting surface 6 is formed by a single endless strand 8 which is wound around a roll assembly so that the adjacent machine direction convolutions of the strand are in closely spaced parallel relation and define the moving supporting surface.

In forming, a very dilute suspension of fibers is extruded onto the freely draining surface 6 which acts as a filter, collecting the fibers in a wet mat and permitting free passage of water between the machine direction elements or convolutions. Thus, the forming surface must filter fibers from the suspension and drain away excess amounts of water, while at the same time it supports and transports the web of loose fibers which have built up upon its surface. To do this effectively, the supporting surface 6 should berelatively open with uniform spacing between adjacent convolutions of the strand. Preferably, to provide free drainage, the strands are impermeable, and may be formed of metal wire; monofilament plastic, such as nylon, polyester or polyacrylic; or plastic impregnated or non-impregnated textile yarn or braid formed of natural or synthetic fibers, or blends of the two.

The roll or guide assembly which supports the strand 8 includes a breast roll or guide member 9 located beneath the slice 5, and the slurry which is discharged through the slice onto the supporting surface 6, is carried over a plurality of table rolls or guide members 10. As the paper web 7 passes over the table rolls 10 a portion of the water in the web is removed and passes through the spaces between adjacent convolutions of the strand 8.

As the web is further advanced by the supporting surface 6 of the endless strand 8, it is subjected to the action of a series of dewatering foils 11, followed by a series of suction boxes 12 which also act to remove a portion of the water from the web. A third sequence of water removal may also be provided by having a suction gland extending the lengthof the driven couch roll 13. Negative pressure applied to the suction gland serves to further extract water from the web.

The roll or guide assembly of the forming section 1 also includes a roll or guide member 14 and a series of guide rolls 15 which are located in planes beneath the table rolls 10. Every other convolution of the strand 8 which defines the web supporting surface 6 passes around the couch roll 13 and downwardly to the guide rolls 15, while the remaining convolutions of the web supporting surface 6 travel over the couch roll 13 to the roll 14 and then downwardly to the guide rolls 15. Therefore, one-half of the convolutions of strand 8 are dropped out or eliminated in the zone between rolls 13 and 14.

The strand 8 may be driven in its endless path by any conventional drive mechanism. As shown diagrammatically in FIG. 3, a motor transmission unit 13a is connected to the shaft 13b of the couch roll 13 and serves to drive the roll 13, thereby driving the strand in its path of travel.

To provide the endless path of travel for the strand 8 the convolution at one side edge of the pattern travels from the end guide roll 15 over a pulley or guide 16 and then travels horizontally to the opposite side of the machine where it passes upwardly around a second pulley 17, passes over the breast roll 9 and reenters the pattern. The specific path of travel followed by the strand 8 will be described in more detail hereinafter.

Following the forming section the paper web is delivered to the press section 2. Pressing is the operation of wringing or extracting water from the wet paper web by passing the web through a set of coacting press rolls 18. The web is conveyed on a supporting structure which serves to (1 support the weak web in the pressure zone (2) uniformly compress the web web so as to obtain maximum pressing efficiency and sheet smoothness, and develop a bond between the fibers, (3) receive water expressed from the web, and (4) transfer the water away from the pressure zone.

As shown in the drawings, a single endless strand 19 is arranged to travel over a roll or guide assembly with turns or convolutions of the strand traveling in the machine direction being located in closely spaced parallel relation to define a web supporting surface 20 which supports the web 7 and advances the web through the press rolls 18. The paper web or sheet 7 is delivered or supplied to the press section 2 by the forming section 1, and as the web passes between the coacting press rolls 18, while supported on the surface 20, water is extracted or removed from the web.

The convolutions of the strand 19 at the supporting surface 20 should be contiguous or relatively close together so as to provide maximum uniformity of support and pressure application. Furthermore, the strand should be permeable so as to accomodate water expressed from the paper web, compressible so as to respond to the pressure zone and apply uniform pressure, and resilient so as to recover from the pressure zone and continually provide voids for accepting expressed water. In a pressing application the surface 23 is visualized as having contiguous strands which when pressed in the nip zone conform to the nip geometry. It has been found that textile yarns composed of either natural or synthetic fibers or filaments or blends in the form of continuous yarns or braided or twisted structures provide these desired characteristics and are particularly satisfactory for use as the strand 19 in the press roll section 2. I

The roll assembly which supports the strand 19 in endless travel includes the roll 14 which also a part of the roll assembly of the forming section 1, rolls or guide members 21, 22 and 23 and a pair of rolls 24 and 25 which are located in planes beneath the rolls 14, 21, 22 and 23. After leaving the nip zone between the press rolls 18 each alternate convolution of the strand 19 is separated from adjacent convolutions and passes downwardly around the roll 22 to the roll 25, while the adjacent convolutions travel around the roll 23 and are reunited with the alternate convolutions at roll 25. The convolutions are again separated with each alternate convolution passing upwardly around the roll 24 to roll 21, while the adjacent convolutions pass upwardly from roll 24 around roll 14 and are reunited with the alternate convolutions at the roll 21 to provide the web supporting surface.

To provide the endless path of travel for the strand 19, the convolution along one side edge of the pattern passes over pulley 26, then moves horizontally to pulley 27 and then travels upwardly around the roll 21 to reenter the pattern at the opposite side of the machine.

Every other turn or convolution of the strand 8 is wound over the roll 14, and similarly, every other turn or convolution of the strand 19 is also wound round the roll 14 and is located in alternating sequence with the convolutions of strand 8. Thus, both the strands 8 and 19 are integrated on the roll 14 to provide a continuous supporting surface for the paper web so that there is no gap or interruption of support for the paper web between the forming and pressing section.

The group of convolutions of strand 19 passing upwardly to roll 14 cross or pass in angular contacting relation with the group of convolutions of strand 8 passing downwardly from roll 14 forming a lease indicated by 28. The contact between adjacent convolutions in the lease area 28 serves a multiple function, in that it not only controls the sequence of consecutive convolutions, but also, due to the doctoring or stripping action, provides a self-cleaning effect for the strands 8 and 19 and automatically spaces the individual convolutions.

One of the press rolls 18 is driven to move the supporting surface 20 and the supported web 7 and to drive the strand 19 in its endless path of travel. As shown diagramatically in FIG. 3, a motor and transmission unit 18a are connected to the shaft 18b of the lower press roll 18 and serves to rotate the roll and thereby move the strand 19 in its endless path of travel.

The drying operation as performed in the drying section 3 entails driving off moisture in the wet web or sheet 7 by means of heat and mass transfer. The dryer section includes a series of heated upper dryer rolls 29 and lower dryer rolls 30, and the paper web 7 is supplied to the dryer section 3 by the press section 2, and as the web passes alternately around the rolls 29 and 30 the moisture in the web is driven off to dry the web. A single endless strand 31, travels over a roll assembly ineluding roll or guide member 23, roll or guide member 32, a group of rolls or guide members 33, which are located between the dryer rolls 30, and rolls 34, 35, and 36. Adjacent machine direction convolutions of the strand serve as the web supporting structure 37 for the paper web 7 and apply uniform pressure against the lower drying rolls 30 to increase heat transfer from the dryer rolls to the paper web. More specifically, the strand 31 passes from roll 23 to roll 32 and then successively under the dryer rolls 30, and over the guide rolls 33. The strand then travels downwardly around the rolls 34, 35 and 36 and then upwardly to roll 32. The strand 31 again passes successively under the dryer rolls 30 and over the guide rolls 33 to provide a second portion of the web supporting surface 37. The strand then moves downwardly over the rolls 34, 35 and 36 and upwardly to the roll 23 where the pattern is repeated. With this winding pattern, the strand 31 is integrated with the strand 19 on the roll 23, with the strands 31 and 19 being in alternating sequence on the roll 23. The integration of the strands 19 and 31 on roll 23 provides a continuous web supporting surface extending from the roll 22 to the roll 32 which will support the wet paper web 7 from the press section 2 to the dryer section 3 without interruption.

The group of convolutions of strand 31 traveling from roll 36 to roll 23 passes in contacting relation with the group of covolutions of strand 19 traveling from roll 23 to roll 25 at a lease area, similar to lease 28.

The strand can be driven in its path of travel by any conventional drive mechanism. As shown diagrammatically in FIG. 3, a motor and transmission unit 30a is connected to the shaft 30b of one of the rolls 30 and serves to rotate the roll and thereby move the strand 31 in its endless path of travel. I

To provide the endless pattern for the strand 31, the convolution at one side edge of the pattern passes from roll 36 over a pulley 38, then travels horizontally to the opposite side edge of the machine, where it travels over a second pulley 39 and passes over, roll23 to reenter the pattern.

In the dryer section 3, the convolutions of the strand are normally located close together to provide maximum heat transfer between the dryer rolls and the paper sheet and the strand itself may be permeable or impermeable depending on the volume of water vapor to be handled.

In addition to the strand 31, a second endless strand 40 is wound over a series of rolls 41 in a series of machine direction convolutions to provide a second surface for the purpose of maintaining contact between the paper sheet and the upper dryer rolls 29 to maximize heat transfer.

To provide the endless pattern for the strand 40 the convolution at one side edge of the pattern passes over a guide or pulley 42, then travels horizontally to the opposite side of the machine where it passes over a second pulley 43 and reenters the pattern in the manner previously described.

The dryer rolls 29 and 30 are driven and this serves to move the web supporting surfaces and thereby move the strands 3 and 40 in their endless paths of travel.

FIG. 3 illustrates in perspective form the winding pattern shown in FIGS. 1 and 2, with the press rolls l8 and the upper rolls 29 not being shown. While FIG. 3 shows only several turns or convolutions of each strand and shows the convolutions in widely spaced relation, in practice, there could be thousands of closely spaced or contiguous convolutions which define the web supporting surface.

FIGS. 4 and are schematic diagrams of a papermaking machine illustrating a manner of providing a continuous web supporting surface having zones of different degrees of porosity. As shown in FIG. 4, the papermaking machine includes a Fourtrinier forming section 1, a press section 2 and a dryer section 3. In the forming section, a single endless strand 44 is wound over a series of rolls 45 51 in a series of generally parallel machine directions loops or convolutions and the portions of the convolutions passing over the rolls or guide members 45, 46, 47 and 48 serve as a web supporting surface to support the paper web 7. In this pattern the strand travels from roll 45 to roll 48, then downwardly around roll 51 to roll 49. The strand then passes upwardly around roll 45 to roll 47 in a second convolution which defines a portion of the web supporting surface, then downwardly to roll 50 and back to roll 49. The strand again passes upwardly around roll 45 to roll 46 in a third convolution and returns to roll 49. Following this, the pattern is repeated with the strand passing upwardly around 45 to roll 48 in a fourth convolution. This results in the zone A of the supporting surface between the rolls 45 arid 46 having a full complement of supporting convolutions, while the zone B of the supporting surface extending between rolls 46 and 47 contains a lesser number of convolutions, and thus has greater porosity, and the zone C of the supporting surface extending between rolls 47 and 48 has a further reduced number of supporting convolutions, thereby resulting in a further increase in porosity.

While the drawings illustrate every third convolution extending the entire length of the supporting surface from roll 45 to 48 and the other convolutions being dropped out, it is contemplated that any desired winding pattern can beutilized so that any number of successive zones can be created, with each zone having a different number of supporting convolutions, and thus a different porosity, than adjacent zones.

The press section includes a pair of cooperating press rolls 52, similar to press rolls previously described. In the press section the endless strand 53 is wound in an endless path, as previously described, over a series of rolls or guide members 54-58, as well as over roll 48, which is also a part of the roll assembly of the forming section 1. In the winding pattern illustrated in FIGS. 4

and 5, the strand 53 moves from roll 48 to roll 56 in a convolution which defines a portion of the web supporting surface and then travels downwardly around rolls 58 and 57 and back to roll 48, where the strand again passes from roll 48 to roll 56 in a second convolution that also defines a portion of the web supporting surface. The strand then passes downwardly around roll 58, upwardly around roll 54 to roll 55 in a path which again constitutes a portion of the web supporting surface. The strand then passes downwardly from roll 55 around roll 57 and back up to roll 48 where the pattern is repeated. As shown in FIG. 5, this winding pattern results in the zone E having a full complement of convolutions in the web supporting surface, while zone D, has a lesser number of web supporting convolutions and a greater degree of porosity. With this winding pattern the press rolls 52 operate in an area E of the web supporting surface having a lesser degree of openness to thereby provide maximum uniformity of pressure application during the pressing operation. The zone F constitutes a transfer zone from the press section 2 to the dryer section 3.

FIGS. 4 and 5, being schematic, show only a single pair of press rolls 52, while in practice there would normally be several pairs of cooperating press rolls in the press section.

In the dryer section 3, a strand 59 is wound in an endless pattern, as previously described, over a series of rolls or guide members 60-65, as well as the roll 56 which also comprises a portion of the roll assembly of the press section. FIGS. 4 and 5, being schematic representations, merely illustrate a pair of lower heated dryer rolls 66 rather than the usual series of dryer rolls, and the upper dryer rolls are not shown. As illustrated in FIG. 4, the strand travels from roll 56 to roll 62 in a convolution which defines a portion of the web supporting surface, then downwardly around rolls 65, 64, 63, and upwardly over roll 60. The strand then passes from roll 60 to roll 62 in a second convolution which also constitutes a portion of the web supporting surface and then travels downwardly around rolls 65 and 64 and back to roll 60. The strand then passes from roll 60 to roll 61 in a third convolution which also comprises a portion of the web supporting surface. After leaving roll 61 the strand travels around rolls 64 and 63 to roll 56 where the pattern is repeated. This winding pattern provides a continuous web supporting surface having different areas of porosity in the dryer section. The area G, as illustrated, is a transfer zone and the zone H has a full complement of web-supporting convolutions and provides maximum support for the paper web, thereby providing maximum heat transfer between the paper web and the dryer roll. The zone I has a decreased number of convolutions resulting in a greater porosity to provide improved egress for water vapor.

The drawings are 'merely diagrammatic illustrations of the winding pattern that can be utilized in accordance with the invention, and while the convolutions defining the web supporting surface are illustrated to be a considerable distance apart, in practice these convolutions may be in closely spaced or contiguous relation. While FIGS. 3 and 5 illustrate only several parallelconvolutions as the web supporting surface, in practice, there may be thousands of adjacent machine direction convolutions that define the web supporting surface.

FIGS. 6 and 7 illustrate a modified form of the invention in which a single strand is employed to provide the web supporting surface in both the forming section and the drying section of a papermaking machine, while a second strand is employed as the web supporting surface in the press section.

FIG. 6 is a diagrammatic illustration of the papermaking machine, including a forming section 67, a press section 68 and a dryer section 69. In this embodiment, an endless strand 70 is arranged to travel over a roll assembly in a series of parallel, machine direction turns or convolutions to provide a supporting surface 71 and the paper pulp slurry is discharged from a slice 72 onto the supporting surface 71 to form a paper web or sheet 73. More specifically, the strand 70 travels from breast roll 74 to couch roll 75, in a series of parallel convolutions which define a portion of the web supporting surface 71, and every other turn or convolution passes downwardly around the roll 75, beneath rolls 76 and 77 and returns to the roll 74. The strand then passes from the roll 74 across roll 75 to roll 78, and then downwardly under rolls 79 and 80, upwardly over rolls 81 and 82 and then under the dryer rolls 83, in the dryer section. The strand 70 then travels beneath rolls 84 and 85 and returns upwardly to roll 82. After passing over roll 82, the strand passes beneath dryer rolls 83 so that a full complement of strands support the paper sheet against the dryer rolls, and then travels beneath rolls 84, 85, 76 and 77 to the roll 74 where the pattern is repeated.

The press section 68 includes a pair of cooperating press rolls 86, similar to press rolls 18, and an endless strand 87 is wound in a series of parallel, machine direction convolutions to provide a web supporting surface 88 that serves to convey the paper web 73 through the nip between the press rolls 86. In the winding pattern, the strand 87 travels from the roll 78, which is a common roll to both the press and forming sections, through the nip between the press rolls 86 in a convolution which constitutes a portion of the web supporting surface 88. The strand then passes downwardly around the lower press roll 86 to roll 89 and then travels around the roll 90 and through the nip in a second convolution of the web supporting surface. Thestrand then passes downwardly around the roll 81 and downwardly beneath the rolls 9] and 92 and returns to the roll 78 where the winding pattern is repeated.

To provide the endless path of travel for the strands 70 and 87, a convolution at one side edge of each winding pattern can pass to the opposite side of the pattern and reenter the pattern in the manner previously described.

FIG. 6 illustrates a pair of lower dryer rolls 83, but in practice a series of upper and lower dryer rolls can be employed, and the convolutions passing around the dryer rolls 83 provide a web supporting surface 93 which provides support for the paper web 72, thereby increasing heat transfer between the paper web and the dryer rolls 80.

The rolls 78 and 81 are common rolls for both the strand 70 and the strand 87 and therefore the paper web 73 is transferred from the forming section 67 to the press section 68 and to the drying section 69 by the integrated strands on the rolls 78 and 81.

In the structure of FIGS. 6 and 7, a single strand 70 is used for both the forming and drying sections, and a separate strand 87, which can have different physical characteristics than strand 70, is used for the press section i In the embodiment shown in FIGS..6 and 7, the portion of the web supporting surface 71 between rolls 74 and 75 has a full complement of convolutions to thereby provide maximum support for the wet paper web, and similarly the portion of the web supporting surface 88 extending between roll 90 and the nip has a full complement of supporting convolutions to provide maximum uniformity of pressure application during the pressing operation.

The strands and 87 can be formed of any of the various types of materials previously described with respect to the first embodiment.

FIG. 8 illustrates a further embodiment of the invention in which strands of different characteristics are integrated to provide a varying porosity for the web supporting surface. FIG. 8 illustrates diagrammatically a portion of a papermaking machine which could either be the forming, pressing or drying section. In this embodiment a strand 94 is wound in a series of parallel machine direction convolutions over a series of rolls 95, 96, 97 and 98. As shown in FIG. 8, every other convolution extends continuously from roll 95 to roll 98, while every alternate convolution extends only from roll 95 to 96.

In addition to the strand 94, a second endless strand 99 is wound in a series of machine direction convolutions over the rolls 97 and 98, as well as over rolls and 101. As illustrated, every other convolution extends continuously from roll 97 to roll 10], while every alternate convolution extends only from roll 100 to 101.

To provide the endless paths of travel from the strands 94 and 99, a convolution at one side edge of each pattern can pass to the opposite side of the pattern and reenter the pattern in the manner previously de' scribed.

In the embodiment of FIG. 8, the strand 94 is provided with different physical characterististics than strand 99 to achieve varying degrees of porosity. As illustrated, strand 94 has a substantially smaller diameter or cross-sectional area than the strand 99 and this difference in diameter provides a change in porosity along the length of the web supporting surface without decreasing the number of web supporting convolutions. For example, the area of the web supporting surface extending between rolls 95 and 96 has a full complement of supporting convolutions, but because the strand 94 has a relatively small diameter the porosity is substantially greater than the porosity of the area located between rolls 100 and 101 which also has a full complement of convolutions of the strand 99. The area of the supporting surface located between rolls 97 and 98 has an intermediate porosity due to the fact that the web supporting surface is composed not only of convolutions of the strand 94, but also of convolutions of the Strand v W. t.

FIG. 8 is a diagrammatic representation, and the spacing and diameter of the strands are exaggerated for purposes of illustration. However, by integrating two or more strands with different properties, i.e., different diameter, configuration, bulk density, fiber material, etc., it is possible to provide an unlimited variation in porosity, compressibility, surface structure, or other physical characteristics along the length of the web supporting surface without materially changing the number of web supporting convolutions.

By eliminating, adding or substituting groups of convolutions in certain zones of the web supporting surface, the porosity or other physical characteristics of the web supporting surface can be varied as desired. This feature also enables the surface formed by a single endless strand of one section to be integrated with the surface formed by the endless strand of adjacent sections so that a continuous web supporting surface is provided throughout the entire papermaking machine.

We claim:

1. In an apparatus for supporting a web impregnated with a fluid, a guide assembly including three generally parallel guide members with the second guide member being located between the first and third guide members, and an endless strand mounted for endless travel on the guide assembly in a series of generally parallel machine direction convolutions a first group of said convolutions extending from the first guide member to the third guide member and defining a portion of a web supporting surface to support and advance the web, a second group of said convolutions extending only from said first guide member to said second guide member and defining a portion of said web supporting surface whereby the area of the web supporting surface located between said second and third guide members contains a lesser number of web supporting convolutions and has a greater porosity than the area of the web supporting surface located between the first and second guide members.

2. The apparatus of claim 1, and including means for supplying a web impregnated with a fluid to the web supporting surface, and means for removing the fluid from the web as it is supported on said web supporting surface.

3. The apparatus of claim 2, and including drive means for driving the strand in an endless path to thereby move the supporting surface and the web supported thereon.

4. The apparatus of claim 1, wherein said guide assembly comprises a portion of the forming section of a paper-making machine and said strand is formed of a water impervious material, and said web is paper.

5. The apparatus of claim 1, wherein said guide assembly comprises a portion of the press section of a paper-making machine and said strand is formed of a compressible resilient water-permeable material, and said web is paper.

6. The apparatus of claim 5, and including pressure means for applying pressure to the paper web supported on the supporting surface.

7. The apparatus of claim 1, wherein the guide assembly comprises a portion of the dryer section of a paper-making machine, and said apparatus includes heating means disposed in contact with the web supported on said supporting surface to thereby aid in removing fluid from said web.

8. The apparatus of claim 1, and including a second guide assembly with said third guide member also being a part of the second guide assembly, a second endless strand mounted for endless travel on said second guide assembly in a series of generally parallel machine direction convolutions with said convolutions constituting a second web supporting surface, said first group of convolutions of said first strand being integrated with convolutions of said second strand on said third guide member, whereby a continuous web supporting surface is provided between said first guide assembly and said second guide assembly.

9. The apparatus of claim 8, in which the integrated convolutions of said first strand and said second strand on said third guide member are disposed in alternating sequence.

10. An apparatus for supporting a sheet impregnated with a fluid, comprising a guide assembly having a series of generally parallel guide members, an endless strand mounted for endless travel on said guide assembly in a series of generally parallel repeating machine direction convolutions, portions of said convolutions defining a moving supporting surface for a fluid impregnated sheet, said strand being mounted on said guide members in a manner to provide a different lateral spacing between adjacent convolutions in a first zone of said supporting surface than in a second zone of said supporting surface, said second zone being disposed in a machine direction with respect to the first zone, said zones being located between adjacent guide members, said first zone having a different porosity than said second zone, whereby the rate of fluid removal from said sheet is different in said first and second zones.

1 l. The apparatus of claim 10, wherein the apparatus is a papermaking machine and the sheet is paper.

12. The apparatus of claim 10, wherein said first and second zones have the same width and said first zone contains a greater number of machine direction convolutions than said second zone.

13. The apparatus of claim 10, wherein said supporting surface includes a third zone disposed longitudinally of said first and second zones in the direction of movement of said supporting surface, said third zone having the same width as said first and second zones and containing a different number of machine direction convolutions than said first and second zones, whereby the porosity of said third zone is different from said first and second zones.

14. The apparatus of claim 13, wherein said guide assembly includes a first roll, a second roll, a third roll and a fourth roll, said first zone extending between said first and second rolls, said second zone extending between said second and third rolls and said third zone extending between said third and fourth rolls, a first group of said machine direction convolutions extending from said first roll to said fourth roll, a second group of machine direction convolutions extending only from said first roll to said third roll and a third group of said machine direction convolutions extending only from said first roll to said second roll, whereby said first zone contains a greater number of machine direction convolutions than said second zone and said second zone contains a greater number of machine direction convolutions than said third zone.

v UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION' Patent No. 3,770,581 Dated November 6, 1973 fls) FRANK H. ORBISON and HOWARD M. HELLAND It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

1 Column 4, line 52, Cancel "web", first occurrence, and substitute therefor --wet--- Column 5, line 20, After "which" insert '--is- Column 10, line 23, Cancel "from" and substitute therefor ---for-+-- Column ll, line 1 Before "We claim" insert ---Vario'u s modes of carrying out the invention are contemplated as being within the scope of the following claims particularly, pointing out and distinctly claiming the subject matter which is regarded as the invention.---

Signed and sealed this 6th day of August 197A.

(SEAL) Attest:

MCCOY M. GIBSON, JR. 0. MARSHALL DANE- Attesting Officer Commissioner of Patents FORM PO-105O (10-69) I 1 USCOMWDC and, I fi LLS. GOVERNMENT PRINTING OFFICE l9, 0-3GG-384. 

2. The apparatus of claim 1, and including means for supplying a web impregnated with a fluid to the web supporting surface, and means for removing the fluid from the web as it is supported on said web supporting surface.
 3. The apparatus of claim 2, and including drive means for driving the strand in an endless path to thereby move the supporting surface and the web supported thereon.
 4. The apparatus of claim 1, wherein said guide assembly comprises a portion of the forming section of a paper-making machine and said strand is formed of a water impervious material, and said web is paper.
 5. The apparatus of claim 1, wherein said guide assembly comprises a portion of the press section of a paper-making machine and said strand is formed of a compressible resilient water-permeable material, and said web is paper.
 6. The apparatus of claim 5, and including pressure means for applying pressure to the paper web supported on the supporting surface.
 7. The apparatus of claim 1, wherein the guide assembly comprises a portion of the dryer section of a paper-making machine, and said apparatus includes heating means disposed in contact with the web supported on said supporting surface to thereby aid in removing fluid from said web.
 8. The apparatus of claim 1, and including a second guide assembly with said third guide member also being a part of the second guide assembly, a second endless strand mounted for endless travel on said second guide assembly in a series of generally parallel machine direction convolutions with said convolutions constituting a second web supporting surface, said first group of convolutions of said first strand being integrated with convolutions of said second strand on said third guide member, whereby a continuous web supporting surface is provided between said first guide assembly and said second guide assembly.
 9. The apparatus of claim 8, in which the integrated convolutions of said first strand and said second strand on said third guide member are disposed in alternating sequence.
 10. An apparatus for supporting a sheet impregnated with a fluid, comprising a guide assembly having a series of generally parallel guide members, an endless strand mounted for endless travel on said guide assembly in a series of generally parallel repeating machine direction convolutions, portions of said convolutions defining a moving supporting surface for a fluid impregnated sheet, said strand being mounted on said guide members in a manner to provide a different lateral spacing between adjacent convolutions in a first zone of saId supporting surface than in a second zone of said supporting surface, said second zone being disposed in a machine direction with respect to the first zone, said zones being located between adjacent guide members, said first zone having a different porosity than said second zone, whereby the rate of fluid removal from said sheet is different in said first and second zones.
 11. The apparatus of claim 10, wherein the apparatus is a papermaking machine and the sheet is paper.
 12. The apparatus of claim 10, wherein said first and second zones have the same width and said first zone contains a greater number of machine direction convolutions than said second zone.
 13. The apparatus of claim 10, wherein said supporting surface includes a third zone disposed longitudinally of said first and second zones in the direction of movement of said supporting surface, said third zone having the same width as said first and second zones and containing a different number of machine direction convolutions than said first and second zones, whereby the porosity of said third zone is different from said first and second zones.
 14. The apparatus of claim 13, wherein said guide assembly includes a first roll, a second roll, a third roll and a fourth roll, said first zone extending between said first and second rolls, said second zone extending between said second and third rolls and said third zone extending between said third and fourth rolls, a first group of said machine direction convolutions extending from said first roll to said fourth roll, a second group of machine direction convolutions extending only from said first roll to said third roll and a third group of said machine direction convolutions extending only from said first roll to said second roll, whereby said first zone contains a greater number of machine direction convolutions than said second zone and said second zone contains a greater number of machine direction convolutions than said third zone. 